5"/51 caliber gun
5"/51 caliber Mark 8 gun on starboard forecastle of USS Texas, March 1914
Type
  • Naval gun
  • Coastal defence
  • Coast Guard gun
    • Place of originUnited States
    Service history
    In service1911–c. 1947
    Used by
    Wars
    Production history
    DesignerBureau of Ordnance
    Designed1910
    Manufacturer
    No. built
    • Mark 7: 93 (Nos. 357–449)
    • Mark 8: 1004 (NGF 539 Nos. 450-unknown)(see builders)
      (No Nos. 1357–1456, 1519–1604 or 1633–1704)
    • Mark 9: 3 (Unknown Nos.)
    • Mark 14: relined Mark 8s
    • Mark 15: enlarged chamber Mark 14s
    VariantsMarks 7, 8, 9, 14, 15
    Specifications
    Mass
    • Mark 7: 11,274 lb (5,114 kg) (with breech)
    • Mark 8: 10,834 lb (4,914 kg) (without breech)
    • Mark 8: 11,300 lb (5,100 kg) (with breech)
    • Mark 9: 10,824 lb (4,910 kg) (without breech)
    • Mark 9: 11,375 lb (5,160 kg) (with breech)
    Length261.25 in (6,636 mm)
    Barrel length255 in (6,500 mm) bore (51 calibers)
    Shell50–55.18 lb (22.68–25.03 kg)
    Caliber5 in (127 mm)
    Breechside swing Welin-type
    Elevation
    • P13: -10° to +20° (late version)
    • P15: -15° to +20°
    • Mark 18: -8.5° to +25°
    Traverseup to 360° depending on location
    Rate of fire8-9 rounds per minute
    Muzzle velocity
    • 3,150 ft/s (960 m/s) (full charge)
    • 2,300 ft/s (700 m/s) (reduced charge)
    Effective firing range17,000 yd (16,000 m) at 20° elevation
    Maximum firing range20,142 yd (18,418 m) at 45° elevation (World War II ammunition)

    5"/51 caliber guns (spoken "five-inch-fifty-one-caliber") initially served as the secondary battery of United States Navy battleships built from 1907 through the 1920s, also serving on other vessels. United States naval gun terminology indicates the gun fired a projectile 5-inch (127 mm) in diameter, and the barrel was 51 calibers long.[1]

    Description

    The different marks of the gun were Marks 7, 8, 9, 14, and 15. The built-up gun consisted of a tube, full-length jacket, and single hoop with side swing Welin breech block and Smith-Asbury mechanism for a total weight of about 5 metric tons. Some Marks included a tapered liner. A 24.5 lb (11.1 kg) charge of smokeless powder gave a 50-pound (23 kg) projectile a velocity of 3,150 ft/s (960 m/s). Range was 15,850 yards (9.0 statute miles or 14.5 kilometres) at the maximum elevation of 20 degrees.[2] Useful life expectancy was 900 effective full charges (EFC) per liner.[3]

    US service

    On a US Navy transport ship c. mid 1942

    The 5-inch/51 caliber gun was designed to engage destroyers, torpedo boats, and other surface targets. The 5"/51 gun entered service in 1911 as secondary armament on the Florida-class battleships, which mounted 16. The guns served well through World War I, but increased awareness of the need for anti-aircraft protection (especially following the attack on Pearl Harbor) encouraged mounting of dual-purpose 5"/38 caliber guns in later battleships, and some of the World War I-era battleships were rearmed with dual purpose guns as well. Surplus 5"/51 guns from scrapped or rearmed battleships were mounted in United States Coast Guard cutters, auxiliaries, small aircraft carriers, coast defense batteries, and Defensively Equipped Merchant Ships.[3] A 1939 Table of Organization and Equipment shows Marine defense battalions were equipped with six of these guns each.[4] 5-inch/51 shore batteries were used with great effectiveness by the 1st Marine Defense Battalion during the Battle of Wake Island in December 1941. These were replaced in the defense battalions by the 155 mm Long Tom gun by 1943. Six Tambor-class submarines were rearmed with "wet mount" 5-inch/51 guns during World War II, taken from Barracuda-class submarines or spares for that class.

    The 5"/51 caliber gun was mounted on:

    Army coast defense use

    5"/51 caliber ex-Navy guns were emplaced during World War II at several locations, some operated by the United States Army Coast Artillery Corps and some by Marine defense battalions. This list may not be exhaustive. They were grouped into two-gun batteries unless otherwise noted.[25]

    British service

    In British service these guns were known as 5"/51 BL Mark VI and Mark VII. During World War I three of these guns formed part of the coastal defences of Scapa Flow.[2] In World War II a small number of these guns entered British service on board ships transferred under the Lend-Lease arrangement. Some of these guns were then transferred to New Zealand (at least six, possibly more) and deployed ashore for coastal defence.[2]

    Surviving examples

    Surviving 5"/51 caliber guns include:[26]

    See also

    Weapons of comparable role, performance and era

    Notes

    1. ^ Fairfield 1921 p. 156
    2. ^ a b c DiGiulian, Tony, "United States of America 5"/51 (12.7 cm) Marks 7, 8, 9, 14 and 15. British 5"/51 (12.7 cm) BL Marks VI and VII
    3. ^ a b Campbell 1985 p.136
    4. ^ Bogart, Charles H., "Fifth Marine Defense Battalion in Iceland", Coast Defense Journal, Vol. 29, Issue 3, August 2015, Coast Defense Study Group, Inc.
    5. ^ Bauer and Roberts, p. 144
    6. ^ a b c Preston 1980 p. 60
    7. ^ a b Breyer 1973 p. 201
    8. ^ a b Breyer 1973 p. 202
    9. ^ a b Breyer 1973 p. 205
    10. ^ a b Friedman 2011 p. 185
    11. ^ a b Breyer 1973 p. 210
    12. ^ a b Breyer 1973 p. 214
    13. ^ a b c Breyer 1973 p. 219
    14. ^ a b Breyer 1973 p. 226
    15. ^ a b c Breyer 1973 p. 230
    16. ^ Bauer and Roberts, pp. 178-179
    17. ^ a b Fahey 1939 p. 18
    18. ^ Bauer and Roberts, p. 265
    19. ^ Fahey 1939 p. 7
    20. ^ Friedman 1983 p. 162
    21. ^ a b c d Friedman 1983 p. 407
    22. ^ Friedman 1983 p. 164
    23. ^ Friedman 1983 p. 170
    24. ^ a b c Fahey 1941 p. 42
    25. ^ Berhow 2015, pp. 216–226.
    26. ^ Berhow, pp. 238-239

    References

    External links

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